physicsgenius
Posts: 5
Joined: Mon Nov 12, 2007 9:35 am

### HELP

Hello!!!! I am conducting the project [Using a laser pointer to measure the data track spacing in a CD] and I was wondering, when i find the data track spacing am I find the data the CD can hold or????? Im also in the process of writing my Literature Review, I am getting help from my physics teacher but if you can clarify what the data track spacing means that would help.

Craig_Bridge
Former Expert
Posts: 1297
Joined: Mon Oct 16, 2006 11:47 am
when i find the data track spacing am I find the data the CD can hold or?????

I'm not sure what you are really asking. Data is stored along a helical data track in the direction of CD rotation. What this experiment is measuring is the spacing between adjacent rotations of the same helix.

In some sense you are finding out something about where one track is centered and where the next is centered or you are finding the spacing of the gap helix (where the data isn't stored) as the two helix have that same pitch.
-Craig

physicsgenius
Posts: 5
Joined: Mon Nov 12, 2007 9:35 am
So I am finding the gap or space between the tracks isn't that called the "land" or is that something else?? Also what do you mean by the two helix have that same pitch?

im sorry if i am being difficult but I am trying to learn as mucha s i can about this topic as possible. Since not a lot of people know about it!!

Craig_Bridge
Former Expert
Posts: 1297
Joined: Mon Oct 16, 2006 11:47 am
If you take a white piece of paper and draw a helix (decreasing radius curve) with a black pencil such that the space between adjacent passes is approximately the same. What you end up with is two concentric helix. One is white (the paper) and the other is black (the pencil line).

"pits" and "lands" are the jargon used for things along the data helix (indentations and the spaces between pits). I'm not aware of the use of "lands" for the gaps between adjacent data track helix.
-Craig

physicsgenius
Posts: 5
Joined: Mon Nov 12, 2007 9:35 am
OHH!!! well thank you that helped??

Do you know any recent people who performed this experiment??? Also what is the significance of the data that will be gained from this experiment??? and what should my Independent variable is [ i was thinking like CD from different companies]????

Craig_Bridge
Former Expert
Posts: 1297
Joined: Mon Oct 16, 2006 11:47 am
Try using the search capabilities on this site. As far as scientific importance, unless you have a hypothesis that you are testing, you aren't doing much more than a demonstration project. Read up on the scientific method on this site and see if you can come up with a hypothesis that you can test to provide some scientific relavance.
-Craig

physicsgenius
Posts: 5
Joined: Mon Nov 12, 2007 9:35 am
AWESOME!!!! hypothesis!!! DUH why didnt I think of that!!! WEll in that case my hypothesis would be a recordale CD would have the most data track spacing out of the other idependent variables [CD-DA, CD-RW] How is that???

physicsgenius
Posts: 5
Joined: Mon Nov 12, 2007 9:35 am

### Re: HELP

Hello!!!
I still need to know what is the data track sapcing in a CD??
Isnt't that the amount of room it has to hold data if so isn't that information already given to you like a 80 minute CD can hold about 700 MB of data!!

vishwa
Former Expert
Posts: 8
Joined: Sun Nov 11, 2007 8:30 am

### Re: HELP

Hi,
You might have had a look at this but just wanted to post this anyway - I think this site would give you a lot of ideas - http://www.sciencebuddies.org/science-f ... p011.shtml
Remember that the more number of times you repeat this (i.e. the larger the number of data sets), the better would be your result. Good luck!

vishwa

Louise
Former Expert
Posts: 921
Joined: Mon Jan 16, 2006 2:17 pm

### Re: HELP

physicsgenius wrote:Hello!!!
I still need to know what is the data track sapcing in a CD??
Isnt't that the amount of room it has to hold data if so isn't that information already given to you like a 80 minute CD can hold about 700 MB of data!!